I agree with op's assertion, however I would point out that ICO team members using their own, verifiable pictures and whatever other docs they release to the public is an excellent act of faith on their part. Of course that doesn't mean investors cannot still get scammed, and examples have been pointed out where that happened.
But when you see an ANN thread for a new project and it comes to light that the team members are all fake, or they're using cartoon avatars instead of their own pictures, that's a sure sign that the project is a scam. That's happened more often than not as far as I can tell.
So I would say that it is *necessary* for those faces to be real, but it is not *sufficient* to ensure that a scam isn't in progress.
RachelX VR project recently did an IEO to 4 exchanges including Vindax and Latoken, their team uses their images but were cartoonized of some sort. I was surprise no one really post a scam reputation about the team and the project. None of the scam busters were trying to question them.
I can see the ANN thread created were bumped by newbie accounts almost everyday but I see they go on, maybe because they were doing IEO but if they were doing ICO, thread must have been filled with scam accusation.